1. Field of the Invention
The present invention relates to motor-driven compressors formed integrally with a compressor device for compressing refrigerant and a motor for driving the compressor device, and more particularly, to motor-driven compressors that are suitable for use in air conditioning systems for vehicles.
2. Description of Related Art
Motor-driven compressors are driven by a power supply, for example, an external power source, such as a battery. Motor-driven compressors formed integrally with a compressor device for compressing refrigerant and a motor for driving the compressor device are known in the art. In known motor-driven compressors, a drive circuit for controlling the operation of the motor is separated from the compressor device and the motor, and an inverter may be coupled to the motor for converting power supplied from a power source into a suitable current for the motor. Such an inverter generally includes a plurality of switching elements. Such switching elements may generate a large amount of heat caused by, for example, electrical loss in the switching elements. Therefore, inverters equipped with cooling devices, such as an air-cooled or a water-cooled type inverter, have been used in known motor-driven compressors. In air-cooled type inverters, a radiator or a fan may be utilized. In water-cooled type inverters, a water cooling radiator and water circulating pipes may be utilized. Such additional equipment increases the cost of manufacturing the automotive air-conditioning system.
A need has arisen to provide motor-driven compressors with drive circuits that do not require additional cooling devices, such as radiators and fans.
In an embodiment of the invention, a motor-driven compressor is formed integrally with a compressor device for compressing refrigerant and a motor for driving the compressor device. The motor-driven compressor comprises a drive circuit and a plurality of cooling fins. The drive circuit controls the operation of the motor. The drive circuit is provided on an outer surface of a wall of a refrigerant suction passage. The plurality of cooling fins are formed on an inner surface of the wall of the refrigerant suction passage.
In another embodiment of the invention, a motor-driven compressor is formed integrally with a compressor device for compressing refrigerant and a motor for driving the compressor device. The motor-driven compressor comprises a drive circuit and a refrigerant flow path. The drive circuit controls the operation of the motor. The drive circuit is attached on an outer surface of a wall of a refrigerant suction passage. The refrigerant flow path is adjacent to an inner surface of the wall opposite the attachment between the driving circuit and the inner surface of the wall.
In still another embodiment of the invention, a motor-driven compressor is formed integrally with a compressor device for compressing refrigerant and a motor for driving the compressor device. The motor-driven compressor comprises a drive circuit and a plurality of ribs. The drive circuit controls the operation of the motor. The drive circuit is attached on an outer surface of a wall of a refrigerant suction passage. The plurality of ribs for reinforcing an annular boss, which supports one end of a drive shaft, are provided on an inner surface of the wall of an attachment portion of the drive shaft.
Objects, features, and advantages of embodiments of this invention will be apparent to persons of ordinary skill in the art from the following detailed description of the invention and the accompanying drawings.